/*
 * This file is part of John the Ripper password cracker,
 *
 * Written by Jim Fougeron <jfoug at cox.net> in 2011.  No copyright
 * is claimed, and the software is hereby placed in the public domain.
 * In case this attempt to disclaim copyright and place the software in the
 * public domain is deemed null and void, then the software is
 * Copyright (c) 2011 Jim Fougeron and it is hereby released to the
 * general public under the following terms:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted.
 *
 * There's ABSOLUTELY NO WARRANTY, express or implied.
 *
 *  This format is:   8hex:8hex  The first 8 hex is the 'starting' crc value
 *  So, if you have a file and its CRC is XYZ, then you would put that value
 *  here, then when the password(s) are found, append them to the file, and get
 *  the final CRC value.  If you want to find a password with the 'proper' CRC
 *  value, then put 0 into the first field.
 *
 *  The 2nd 8 hex value is what we are looking for.
 *
 * If you want alternate plaintexts, run with --keep-guessing option.
 */

#if FMT_EXTERNS_H
extern struct fmt_main fmt_crc32;
#elif FMT_REGISTERS_H
john_register_one(&fmt_crc32);
#else

#include <string.h>

#include "arch.h"
#if !FAST_FORMATS_OMP
#undef _OPENMP
#endif
#ifdef _OPENMP
#include <omp.h>
#endif

#include "common.h"
#include "formats.h"
#include "crc32.h"
#include "loader.h"

#define FORMAT_LABEL			"CRC32"
#define FORMAT_NAME			""
#define FORMAT_TAG			"$crc32$"
#define FORMAT_TAG_LEN		(sizeof(FORMAT_TAG)-1)
#define FORMAT_TAGc			"$crc32c$"
#define FORMAT_TAGc_LEN		(sizeof(FORMAT_TAG)-1)
#define ALGORITHM_NAME			"CRC32 32/" ARCH_BITS_STR " CRC-32C " CRC32_C_ALGORITHM_NAME
#define BENCHMARK_COMMENT		""
#define BENCHMARK_LENGTH		0

#define PLAINTEXT_LENGTH		31

#define BINARY_SIZE			4
#define BINARY_ALIGN			4
#define SALT_SIZE			5
#define SALT_ALIGN			4

#ifndef OMP_SCALE
#define OMP_SCALE       2 // tuned w/ MKPC for core i7
#endif

#define MIN_KEYS_PER_CRYPT		1
#define MAX_KEYS_PER_CRYPT		8192

static struct fmt_tests tests[] = {
	{"$crc32$00000000.fa455f6b", "ripper"},
	{"$crc32$00000000.4ff4f23f", "dummy"},
//	{"$crc32$00000000.00000000", ""},         // this one ends up skewing the benchmark time, WAY too much.
	{"$crc32$4ff4f23f.ce6eb863", "password"}, // this would be for file with contents:   'dummy'  and we want to find a password to append that is 'password'
	{"$crc32$fa455f6b.c59b2aeb", "123456"},   // ripper123456
	{"$crc32c$00000000.98a61e94", "ripper"},
	{"$crc32c$00000000.d62b95de", "dummy"},
//	{"$crc32c$00000000.00000000", ""},         // this one ends up skewing the benchmark time, WAY too much.
	{"$crc32c$d62b95de.1439c9f9", "password"}, // this would be for file with contents:   'dummy'  and we want to find a password to append that is 'password'
	{"$crc32c$98a61e94.77f23179", "123456"},   // ripper123456
	{NULL}
};

static struct fmt_main *pFmt;
static char (*saved_key)[PLAINTEXT_LENGTH + 1];
static CRC32_t (*crcs);
static CRC32_t crcsalt;
static unsigned int crctype;

static void init(struct fmt_main *self)
{
	omp_autotune(self, OMP_SCALE);

	saved_key = mem_calloc(self->params.max_keys_per_crypt,
	                       sizeof(*saved_key));
	crcs      = mem_calloc(self->params.max_keys_per_crypt,
	                       sizeof(*crcs));

	pFmt = self;
}

static void done(void)
{
	MEM_FREE(crcs);
	MEM_FREE(saved_key);
}

static int valid(char *ciphertext, struct fmt_main *self)
{
	char *p, *q;
	int i;

	if (strncmp(ciphertext, FORMAT_TAG, FORMAT_TAG_LEN) && strncmp(ciphertext, FORMAT_TAGc, FORMAT_TAGc_LEN))
		return 0;

	p = strrchr(ciphertext, '$');
	q = strchr(p, '.');
	if (!q || q-p != 9)
		return 0;
	for (i = 0; i < 8; ++i) {
		int c1 = ARCH_INDEX(p[1+i]);
		int c2 = ARCH_INDEX(p[10+i]);
		if (atoi16[c1] == 0x7F || atoi16[c2] == 0x7F)
			return 0;
/* We don't support uppercase hex digits here, or else we'd need to implement
 * split() and set FMT_SPLIT_UNIFIES_CASE. */
		if (c1 >= 'A' && c1 <= 'F')
			return 0;
		if (c2 >= 'A' && c2 <= 'F')
			return 0;
	}
	return 1;
}

#define COMMON_GET_HASH_VAR crcs
#include "common-get-hash.h"

static void *get_binary(char *ciphertext)
{
	static uint32_t *out;
	char *p;
	if (!out)
		out = mem_alloc_tiny(sizeof(uint32_t), MEM_ALIGN_WORD);
	p = strchr(ciphertext, '.');
	sscanf(&p[1], "%x", out);
	// Performing the complement here, allows us to not have to complement
	// at the end of each crypt_all call.
	*out = ~(*out);
	return out;
}

static void *get_salt(char *ciphertext)
{
	static uint32_t *out;
	char *cp;

	if (!out)
		out = mem_alloc_tiny(sizeof(uint32_t)*2, MEM_ALIGN_WORD);
	cp = strrchr(ciphertext, '$');
	sscanf(&cp[1], "%x", out);
	// since we ask for the crc of a file, or zero, we need to complement here,
	// to get it into 'proper' working order.
	*out = ~(*out);
	if (!strncmp(ciphertext, FORMAT_TAG, FORMAT_TAG_LEN))
		((char*)out)[4] = 0;
	else
		((char*)out)[4] = 1;
	return out;
}

static void set_key(char *key, int index)
{
	strnzcpy(saved_key[index], key, sizeof(*saved_key));
}

static char *get_key(int index)
{
	return saved_key[index];
}

static int crypt_all(int *pcount, struct db_salt *salt)
{
	const int count = *pcount;
	int i;

	switch (crctype) {

	case 0:
#ifdef _OPENMP
#pragma omp parallel for private(i)
#endif
		for (i = 0; i < count; ++i) {
			CRC32_t crc = crcsalt;
			unsigned char *p = (unsigned char*)saved_key[i];
			while (*p)
				crc = jtr_crc32(crc, *p++);
			crcs[i] = crc;
			//printf("%s() In: '%s' Out: %08x\n", __FUNCTION__, saved_key[i], ~crc);
		}
		break;

	case 1:
#ifdef _OPENMP
#pragma omp parallel for private(i)
#endif
		for (i = 0; i < count; ++i) {
			CRC32_t crc = crcsalt;
			unsigned char *p = (unsigned char*)saved_key[i];
			while (*p)
				crc = jtr_crc32c(crc, *p++);
			crcs[i] = crc;
			//printf("%s() In: '%s' Out: %08x\n", __FUNCTION__, saved_key[i], ~crc);
		}

	}

	return count;
}

static void set_salt(void *salt)
{
	crcsalt = *((uint32_t *)salt);
	crctype = ((char*)salt)[4];
}

static int cmp_all(void *binary, int count)
{
	uint32_t crc=*((uint32_t*)binary), i;
	for (i = 0; i < count; ++i)
		if (crc == crcs[i]) return 1;
	return 0;
}

static int cmp_one(void *binary, int index)
{
	return *((uint32_t*)binary) == crcs[index];
}

static int cmp_exact(char *source, int index)
{
	return 1;
}

static int salt_hash(void *salt)
{
	return *(uint32_t*)salt & (SALT_HASH_SIZE - 1);
}

static unsigned int crc32_ver(void *salt)
{
	char *my_salt = (char*)salt;

	return (unsigned int)my_salt[4];
}

struct fmt_main fmt_crc32 = {
	{
		FORMAT_LABEL,
		FORMAT_NAME,
		ALGORITHM_NAME,
		BENCHMARK_COMMENT,
		BENCHMARK_LENGTH,
		0,
		PLAINTEXT_LENGTH,
		BINARY_SIZE,
		BINARY_ALIGN,
		SALT_SIZE,
		SALT_ALIGN,
		MIN_KEYS_PER_CRYPT,
		MAX_KEYS_PER_CRYPT,
#ifdef _OPENMP
		FMT_OMP | FMT_OMP_BAD |
#endif
		FMT_CASE | FMT_8_BIT,
		{
			"version [0:CRC-32 1:CRC-32C]",
		},
		{ FORMAT_TAG, FORMAT_TAGc },
		tests
	}, {
		init,
		done,
		fmt_default_reset,
		fmt_default_prepare,
		valid,
		fmt_default_split,
		get_binary,
		get_salt,
		{
			crc32_ver,
		},
		fmt_default_source,
		{
			fmt_default_binary_hash_0,
			fmt_default_binary_hash_1,
			fmt_default_binary_hash_2,
			fmt_default_binary_hash_3,
			fmt_default_binary_hash_4,
			fmt_default_binary_hash_5,
			fmt_default_binary_hash_6
		},
		salt_hash,
		NULL,
		set_salt,
		set_key,
		get_key,
		fmt_default_clear_keys,
		crypt_all,
		{
#define COMMON_GET_HASH_LINK
#include "common-get-hash.h"
		},
		cmp_all,
		cmp_one,
		cmp_exact
	}
};

#endif /* plugin stanza */
